JP2008074491A - Sterilization method for food container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to sterilize a bacteria spore attached to a food container with a low-concentration medicine. <P>SOLUTION: Prior to sterilization with water containing hypochlorous acid, it is brought into contact with an alkaline water solution. An fine acid electrolyzed water which has established available chlorine concentration as the range of 1-50 ppm or a sodium hypochlorite water solution which has established the available chlorine concentration as the range of 1-50 ppm is used for the water containing the hypochlorous acid, and an NaOH water solution of which the pH is 11-14 and of which the water temperature has established as 50-80 °C is used for the alkaline water solution. This kind of method is suitable for a bottle-washing process and capable of reducing water consumption sharply since an exiting apparatus can be almost utilized as it is. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for sterilizing food containers such as glass bottles, PET bottles, and plastic containers.

  Food containers are often sterilized prior to food storage so that the food to be stored does not spoil. At that time, if the food to be stored is a low acid food having a bacteriostatic effect, fungi and yeast having low heat resistance may be sterilized, and heat sterilization may be performed with hot water or the like. However, neutral foods to which many foods are applicable have no bacteriostatic effect, and it is necessary to sterilize even spore-forming bacteria (spore bacteria) that form extremely resistant spores. For example, Bacillus cereus, which is a food-toxic spore bacteria, has a strain that grows even at a low temperature of 10 ° C. or lower, and sterilized foods such as city milk require sterilization. Unlike other spores, On the outer side of the spore shell, there is even an outer skin (exosporium) that is thought to be a medicinal barrier. For this reason, sufficient sterilization effect cannot be obtained for spores only by heat sterilization. For example, the sterilization effect can be improved by combined use of chemical sterilization agents such as chlorine-based, peracetic acid-based and ozone water. ing. Nevertheless, the sterilization conditions must be excessive (high concentration), and various problems have arisen accordingly. For example, peracetic acid-based disinfectants are not approved as food additives, so after sterilization treatment, it is necessary to rinse with a large amount of water, which is extremely uneconomical, and ozone water also generates harmful ozone gas. Therefore, the processing is difficult.

  The same is true for an aqueous solution of sodium hypochlorite (chlorine water) that is common as a chlorine-based disinfectant, and a strong chlorine odor remains when used at a concentration (for example, 50 to 200 ppm) at which a practical disinfectant effect can be obtained. In order to remove the chlorine odor, a rinsing treatment with a large amount of water is required. There are also problems of generation of off-flavors such as chlorine compounds (chloramines) produced by reaction with organic substances and generation of trihalomethane, which is a carcinogen.

  By the way, recently, electrolyzed water has attracted attention as a sterilizing means replacing chlorine water. The electrolyzed water refers to, for example, functional water obtained by electrolyzing water to which hydrochloric acid, sodium chloride or the like is added, and includes strongly acidic electrolyzed water and slightly acidic electrolyzed water (weakly acidic electrolyzed water). These active ingredients are considered to be hypochlorous acid as the main component of the bactericidal action, as is the case with the sodium hypochlorite aqueous solution. Due to the difference in pH, even if the effective chlorine concentration is lower than that of the sodium hypochlorite aqueous solution, an excellent bactericidal effect is exhibited.

  A sterilization method using electrolyzed water has also been proposed (Patent Documents 1 to 3). For example, Patent Document 1 uses electrolytic acid water and ultraviolet rays in combination. Patent Document 2 discloses a sterilization method for improving the sterilization effect by germinating spores prior to sterilization treatment with acidic electrolyzed water, targeting spore bacteria attached to the surface of spices and the like. Patent Document 3 discloses a method for washing and sterilizing chicken eggs in which eggshells are washed with acetic acid and then sterilized with weakly acidic electrolyzed water.

JP-A-9-154924 JP 2003-61610 A JP 2005-27609 A

  However, the ultraviolet rays in Patent Document 1 have a big problem that the bactericidal effect cannot be obtained unless the microorganisms are directly irradiated, and the method of Patent Document 2 lacks certainty because spores that have not germinated cannot be sterilized. In the method of Patent Document 3, a spore containing Bacillus cereus is targeted, but in order to sterilize the spore, an effective chlorine concentration of at least 150 ppm is required.

  Although various investigations have been made, after all, no sterilization means that can effectively sterilize highly resistant spores have been established.

  That is, an object of the present invention is to provide a food container sterilization method capable of effectively sterilizing spore bacteria while having an appropriate drug concentration that does not cause a problem. An object of the present invention is to provide a method for sterilizing a food container that can effectively sterilize Bacillus cereus which is difficult to sterilize by efficiently using electrolyzed water or chlorinated water. An object of the present invention is to provide a food container sterilization method that can use existing manufacturing equipment as it is and is highly practical.

  The present inventors pay attention to the fact that the main component constituting the spores of the spore is a protein, and it is thought that if the surface structure is altered, the medicinal effect on the spore, that is, the bactericidal effect can be improved. The present inventors have found that an excellent bactericidal effect can be obtained by combining processing conditions, and have completed the present invention. The method for sterilizing a food container according to the present invention comprises a pre-sterilization step of bringing a food container into contact with an alkaline aqueous solution, and a sterilization step of sterilizing the food container brought into contact with the alkaline aqueous solution with hypochlorous acid-containing water. And Here, hypochlorous acid-containing water means an aqueous solution containing hypochlorous acid as an active ingredient, and a concept including an aqueous solution of sodium hypochlorite and various electrolyzed waters containing hypochlorous acid as an active ingredient. is there. The alkaline aqueous solution means an aqueous solution showing strong alkalinity such as NaOH and KOH.

  NaOH aqueous solution (sodium hydroxide aqueous solution) is used for alkaline aqueous solution, pH can be set in the range of 11-14, and the water temperature can be set in the range of 50-80 degreeC. The reason why the pH was set to 11 or more is that deactivation of the enzyme was observed and it was effective for protein denaturation. The reason why the water temperature is set to 50 ° C. or higher is that a protein denaturation action by heating is obtained, which is more effective, and bacterial cells other than spores, molds and yeasts can be sterilized. The reason why the temperature is set to 80 ° C. or lower is that the food container itself may be damaged and the heat efficiency is poor.

  Specifically, slightly acidic electrolyzed water is used as hypochlorous acid-containing water, and the pH can be set in the range of 4 to 7 and the effective chlorine concentration can be set in the range of 1 to 50 ppm. Alternatively, a sodium hypochlorite aqueous solution can be used for the hypochlorous acid-containing water, and the pH can be set in the range of 6.5 to 9 and the effective chlorine concentration can be set in the range of 1 to 50 ppm. Preferably, in both cases of slightly acidic electrolyzed water and aqueous sodium hypochlorite solution, the effective chlorine concentration is set in the range of 5 to 20 ppm. This is because when the concentration is less than 1 ppm, a practical bactericidal effect by hypochlorous acid cannot be obtained, and when it exceeds 50 ppm, problems such as residual chlorine odor occur. In addition, the pH of the slightly acidic electrolyzed water is 4-7 and the pH of the sodium hypochlorite aqueous solution is 6.5-9. Hypochlorous acid is stable in this range, and a high bactericidal effect is obtained. This is because it is understood.

  Moreover, the food container sterilization method of the present invention was applied to the bottle washing step shown in FIG. 13, and the washing step for washing the bottle with washing water, the rinsing step for rinsing the washed bottle with water, and the rinsing A sterilization method comprising a pre-sterilization step in which a bottle is brought into contact with an alkaline aqueous solution and a sterilization step in which the bottle brought into contact with the alkaline aqueous solution is sterilized with slightly acidic electrolyzed water. Here, the term “bottle” is not limited to a glass bottle, but is a concept including a plastic bottle such as a plastic bottle, a metal can, a paper container (lamination processing), and the like.

  Further, the cleaning process includes a cleaning process for cleaning the bottle with cleaning water, a rinsing process for rinsing the cleaned bottle with water, and a sterilization process for sterilizing the rinsed bottle with slightly acidic electrolyzed water. May be an alkaline aqueous solution, and the washing step may also serve as a pre-sterilization step.

  The washing process includes a washing process for washing the bottle with washing water and a rinsing process for rinsing the washed bottle. The washing water used in the washing process is an alkaline aqueous solution, and the water used in the rinsing process is used as slightly acidic electrolyzed water. May be a pre-sterilization step, and the rinse step may also be a sterilization step.

  NaOH aqueous solution is used for alkaline aqueous solution, pH can be set in the range of 11-14, and water temperature can be set in the range of 50-80 degreeC. Further, the slightly acidic electrolyzed water can be set to a pH of 4 to 7 and an effective chlorine concentration of 1 to 50 ppm.

  Further, the food sterilization method of the present invention is applied to the bottle washing step shown in FIG. 13, a washing step for washing the bottle with washing water, a rinsing step for rinsing the washed bottle with water, and a rinsed bottle It can be set as the sterilization method provided with the pre-sterilization process made to contact alkaline aqueous solution, and the sterilization process which sterilizes the bottle contacted with alkaline aqueous solution with sodium hypochlorite aqueous solution.

  Further, the cleaning process includes a cleaning process for cleaning the bottle with cleaning water, a rinsing process for rinsing the cleaned bottle with water, and a sterilization process for sterilizing the rinsed bottle with an aqueous sodium hypochlorite solution. The washing water may be an alkaline aqueous solution, and the washing step may also serve as a pre-sterilization step.

  A washing process for washing the bottle with washing water and a rinsing process for rinsing the washed bottle, the washing water used in the washing process as an alkaline aqueous solution, and the water used in the rinsing process as a sodium hypochlorite aqueous solution, The washing process may also serve as the pre-sterilization process, and the rinse process may serve as the sterilization process.

  NaOH aqueous solution is used for alkaline aqueous solution, pH can be set in the range of 11-14, and water temperature can be set in the range of 50-80 degreeC. In addition, the aqueous sodium hypochlorite solution can be set to a pH of 6.5 to 9 and an effective chlorine concentration of 1 to 50 ppm.

  Prior to sterilization with hypochlorous acid-containing water, excellent sterilization far exceeds the sterilization effect obtained with hypochlorous acid-containing water alone or alkaline aqueous solution alone by performing pre-sterilization treatment in contact with alkaline aqueous solution The effect was able to be acquired. Although the mechanism has not been verified, contacting the spore with an alkaline aqueous solution prior to sterilization alters the surface structure of the spore spore shell or coat and significantly reduces the drug resistance to hypochlorous acid of the spore. It is assumed that it is possible to make it.

  When an aqueous NaOH solution having a pH of 11 to 14 and a water temperature of 50 to 80 ° C. is used as the alkaline aqueous solution, the organic soil is effectively removed, and mold, yeast and general bacteria are removed. Can be surely sterilized, and can efficiently alter the spore shell and coat of the spore. The NaOH to be used is advantageous in that it is an inexpensive chemical that is widely used in food production facilities.

  As hypochlorous acid-containing water, slightly acidic electrolyzed water whose pH is in the range of 4-7 and effective chlorine concentration is set in the range of 1-50 ppm, or in the range of pH 6.5-9, effective chlorine concentration Is a low-concentration sodium hypochlorite aqueous solution set in the range of 1 to 50 ppm. This makes it possible to effectively sterilize spores despite the low effective chlorine concentration, which has hardly achieved a bactericidal effect in the past, and solves the problems of odors such as chlorine odor and trihalomethane at once. can do.

  The food container is a bottle, the washing step for washing the bottle with washing water, the rinsing step for rinsing the washed bottle with water, the pre-sterilization step for bringing the rinsed bottle into contact with the alkaline aqueous solution, and the contact with the alkaline aqueous solution According to the sterilization method including the sterilization step of sterilizing the bottle with slightly acidic electrolyzed water or a low-concentration sodium hypochlorite aqueous solution, a series of conventionally used washing bottle facilities can be used as they are. That is, it is only necessary to apply the sterilization method of the present invention in place of the sterilization process with a high concentration sodium hypochlorite aqueous solution in the conventional washing bottle process.

  If the washing water used in the washing process is made into an alkaline aqueous solution so that the washing process also serves as a pre-sterilization process, the process can be simplified and the amount of chemicals and water used can be greatly reduced. Can be improved.

  Furthermore, if the water used in the rinsing process is replaced with slightly acidic electrolyzed water or a low-concentration sodium hypochlorite aqueous solution so that the rinsing process also serves as a sterilization process, the process can be further simplified and used. Equipment and water volume can be dramatically reduced, and productivity can be significantly improved.

(First embodiment)
The first embodiment of the present invention will be described below with reference to the drawings. First, conditions and effects of the sterilization method according to the present embodiment will be specifically described based on test results. In the test, a glass container was used, and the prepared spore solution was treated by the sterilization method according to the present embodiment, and the number of remaining after treatment (number of surviving spores) was examined.

{Adjustment of spore fluid}
In the test, spores of Bacillus cereus B-164 (derived from milk) were used. Bacillus cereus was cultured in Ca (0.1%)-SMA medium at 30 ° C. for 1 week. The obtained colonies of Bacillus cereus were suspended in sterile physiological saline. The suspension was washed repeatedly by centrifugation (3000 rpm, 15 minutes) three times, then heated at 80 ° C. for 10 minutes to sterilize only vegetative cells, and this was used as a spore solution for the test. In addition, the spore concentration of the obtained spore fluid (stock solution) was about 10 8 cfu / ml. The number of bacteria (spore number) was measured by the pour method (cfu / ml) in a standard agar medium and cultured at 30 ° C. for 48 hours.

{Alkaline aqueous solution}
An aqueous NaOH solution adjusted to a concentration of 1 (w / vol)% by dissolving NaOH (sodium hydroxide) in purified water was used as an alkaline aqueous solution. The pH of this alkaline aqueous solution was 13.5.

{Hypochlorous acid-containing water}
Slightly acidic electrolyzed water produced using an existing membrane-type electrolyzed water production apparatus was used. Examples of this type of electrolyzed water production apparatus include “Hycrosoft Water Generator (Well CLEAN-TE NDX-65KM-H, manufactured by Oak Co., Ltd.)”, “Sterilized Washing Water Generator (ACDION250, Nippon Aqua Sales Co., Ltd.) And "Slightly acidic electrolyzed water generator (Purestar Mp-240E, manufactured by Morinaga Milk Industry Co., Ltd.)". The slightly acidic electrolyzed water (stock solution) obtained from the production apparatus had an effective chlorine concentration of about 60 ppm and a pH of 6.7. This slightly acidic electrolyzed water (stock solution) diluted with sterilized water and adjusted to a predetermined effective chlorine concentration (1, 5, 10, 20 ppm) was subjected to the test. The pH of each slightly acidic electrolyzed water (test solution) after dilution was in the range of 6.7 to 6.8, and there was almost no change. In addition, about the slightly acidic electrolyzed water whose effective chlorine concentration is 1 ppm, the effective chlorine concentration was measured by DPD method. Moreover, about the slightly acidic electrolyzed water of other effective chlorine concentration, the effective chlorine concentration was measured by the iodometry method.

{Pre-sterilization process}
10 ml of an alkaline aqueous solution placed in a dilution bottle was placed in a 75 ° C. constant temperature water bath and stabilized at 75 ° C. while stirring with a stirrer, and then 0.1 ml of a spore solution (stock solution) was inoculated therein and retained. After the elapsed time (treatment time) after inoculation of the spore fluid was 8.5 minutes, 10 ml of the alkaline aqueous solution inoculated with the spore fluid (stock solution) was immediately ice-cooled with 40 ml of 0.2 M phosphate buffer. While adding (pH 6.4) and quenching, the pH was neutralized to obtain an alkali-treated spore solution.

{Sterilization process}
A sterilized bottle containing 100 ml of each slightly acidic electrolyzed water adjusted to each effective chlorine concentration of 1, 5, 10, and 20 ppm was placed in a constant temperature water bath at 20 ° C. and stabilized at 20 ° C. while stirring with a stirrer. After stabilization, 1 ml of the previous alkali-treated spore solution was added to each sterilized bottle. Then, after each predetermined time (reaction time), 1 ml from each sterilization bottle is removed with a pipette, and immediately added to and stirred in a test tube containing 4 ml of ice-cooled 0.1N sodium thiosulfate solution. Was neutralized to obtain a sterilized spore solution. About each sterilization processing spore liquid, the number of residual bacteria (survival spore number) was measured (test A). In order to measure the bactericidal effect of the slightly acidic electrolyzed water alone, the same treatment was carried out on the spore liquid not subjected to the pre-sterilization step simultaneously with this test (Control A).

  (Bactericidal effect of alkaline aqueous solution alone) Prior to this test, the results of confirming the sterilizing effect of the spore in the pre-sterilization step alone are shown in the graph of FIG. About the previous alkali-treated spore solution, the number of bacteria (number of spores) before and after the treatment was repeatedly measured, and the measurement results were compared (N number = 6). As is clear from the graph, the bactericidal effect was 0.5D to 0.9D, and only a bactericidal effect of 1D or less was observed. In addition, "D" here represents the bactericidal effect, and represents the number of bacteria per ml as a common logarithm (LOG value), and the number of bacteria before the treatment (LOG value). A value obtained by subtracting a number (LOG value) is shown.

  (Bactericidal effect under test conditions) The test results obtained under the test conditions described above are shown in Table 1 and FIGS. The vertical axis in FIGS. 2 to 5 represents the number of remaining bacteria (number of surviving spores) (LOG value), and the horizontal axis represents the reaction time (minutes). Under conditions without the pre-sterilization step performed as Control A (slightly acidic electrolyzed water alone), almost no bactericidal effect was obtained at any effective chlorine concentration. On the other hand, according to the method (test A) according to the present embodiment, a bactericidal effect is observed at 1 ppm or more, and particularly at 5 ppm or more, as shown in FIG. An excellent bactericidal effect of 6D or more was observed. In other words, prior to sterilization with slightly acidic electrolyzed water, by performing a sterilization pretreatment in contact with an alkaline aqueous solution, an excellent sterilizing effect far exceeding the sterilizing effect obtained with the slightly acidic electrolyzed water alone or the alkaline aqueous solution alone is achieved. I was able to get it. Although the mechanism has not been verified yet, the spore shell or outer surface structure of the spore is dissolved and altered by bringing the spore into contact with a strong alkaline aqueous solution prior to sterilization, resulting in hypochlorous acid in the spore. It is presumed that it is possible to remarkably reduce the drug resistance against.

  (Influence of treatment time in pre-sterilization process) Next, the influence of the length of the treatment time in the pre-sterilization process on the sterilization effect of slightly acidic electrolyzed water was confirmed. In the pre-sterilization step, an alkali-treated spore solution with treatment times of 0.5, 1, 2, 3, 4, 5, 6, 7, and 8.5 minutes was obtained. The above-mentioned sterilization process was performed on the alkali-treated spore solution set for each treatment time, and the number of remaining bacteria (number of surviving spore) was measured (Test B). However, in the sterilization process, slightly acidic electrolyzed water having an effective chlorine concentration of 5 ppm was used, and the reaction time was 5 minutes. Moreover, in order to confirm the influence which the length of processing time has on the bactericidal effect by alkaline aqueous solution single, the number of bacteria (spore number) before and behind the process of the pre-sterilization process was measured (control B).

  Table 2 shows the bactericidal effect of slightly acidic electrolyzed water in each treatment time. As is clear from Table 2, the alkaline aqueous solution alone (Control B) has a bactericidal effect of 0.5 D or less regardless of the length of the treatment time. On the other hand, in the test B, the bactericidal effect of 1 to 1D or more was recognized for the treatment time, which was almost the maximum (3.1D) in 6 minutes. That is, it was confirmed that the longer the time for which the spore was brought into contact with the strongly alkaline aqueous solution, the greater the bactericidal effect of the slightly acidic electrolyzed water.

  (Influence of other test conditions) The influence on the effect of the sterilization method according to the present embodiment when an alkaline aqueous solution containing other chemicals was used in the pre-sterilization process was confirmed. That is, in the pre-sterilization step, an Ecline 110 (Riko Kyosan Co., Ltd.) aqueous solution adjusted to a concentration of 1 (w / vol)% was used as the alkaline aqueous solution. In addition, pH of 1% concentration Ecrine No. 110 aqueous solution was 13.5. The above-mentioned sterilization step was performed on the alkali-treated spore solution using 1% concentration of Ecline No. 110 aqueous solution, and the number of remaining bacteria (number of surviving spores) was examined. As a result, the same bactericidal effect as Test A was obtained even when 1% concentration of Ecline No. 110 aqueous solution was used. From this, it was confirmed that not only an aqueous solution of NaOH alone but also an aqueous solution containing other chemicals can be used for the pre-sterilization step as the alkaline aqueous solution.

  Moreover, it confirmed about the influence which the difference in the epidermis structure of a spore exerts on the effect of the sterilization method which concerns on this Embodiment. That is, using each spore of Bacillus subtilis (B-162, derived from milk) and Bacillus licheniformis (No. 33, derived from yogurt), which is a kind of spore fungus, a spore solution prepared in the same manner as the spore solution of Bacillus cereus, It processed by the above-mentioned sterilization method, and the number of residual bacteria (number of living residual spores) in each spore liquid was investigated. As a result, the same bactericidal effect as test A was obtained. In addition, Bacillus subtilis and Bacillus licheniformis do not have exosporium, and Bacillus subtilis and Bacillus licheniformis have an epidermis structure called exosporium. From this, it was confirmed that the sterilization method according to the present embodiment can provide an excellent sterilization effect on a wide range of spores regardless of the epidermis structure of the spores.

(Second Embodiment)
Next, conditions and effects of the sterilization method according to the second embodiment of the present invention will be described based on the test results, focusing on differences from the first embodiment. The sterilization method according to the present embodiment is different from the sterilization method according to the first embodiment in that low-concentration chlorine water is used instead of slightly acidic electrolyzed water. Low concentration chlorine water means an aqueous sodium hypochlorite solution having an effective chlorine concentration of 1 to 50 ppm.

{Hypochlorous acid-containing water}
A sodium hypochlorite aqueous solution (stock solution) having an effective chlorine concentration of 7 to 8 (w / vol)% diluted with sterilized water and adjusted to a predetermined effective chlorine concentration (1, 5, 10, 20 ppm) The test was conducted as low-concentration chlorine water. The pH of the low-concentration chlorine water (test solution) adjusted to each effective chlorine concentration was in the range of 6.7 to 8.9. Note that the concentration of sodium hypochlorite in the low-concentration chlorine water (test solution) coincides with the effective chlorine concentration. Moreover, about the low concentration chlorine water whose effective chlorine concentration is 1 ppm, the effective chlorine concentration was measured by DPD method. For other low-concentration chlorine water having an effective chlorine concentration, the effective chlorine concentration was measured by an iodometry method.

{Sterilization process}
In the sterilization step described in the above embodiment, low-concentration chlorine water (test solution) adjusted to each effective chlorine concentration of 1, 5, 10, 20 ppm was used instead of the slightly acidic electrolyzed water. Thereby, the bactericidal treatment spore liquid using the low concentration chlorine water adjusted to each effective chlorine concentration was obtained. For each sterilized spore solution, the number of remaining bacteria (number of surviving spores) was measured (Test C). Simultaneously with test C, the bactericidal effect of low-concentration chlorine water alone was measured. That is, using the low-concentration chlorine water adjusted to each effective chlorine concentration, the same treatment as the sterilization step described in the above embodiment was performed on the spore liquid that had not been subjected to the pre-sterilization step (Control C).

  (Bactericidal effect under test conditions) The test results obtained under the test conditions described above are shown in Table 3 and FIGS. The vertical axis | shaft of FIGS. 7-10 has shown the number of residual bacteria (survival spore number) (LOG value), and the horizontal axis has shown reaction time (minute). Under the conditions without the pre-sterilization step performed as Control C (low concentration chlorine water alone), almost no bactericidal effect was obtained at any effective chlorine concentration. On the other hand, according to the sterilization method according to the present embodiment (Test C), the sterilization effect is recognized at 1 ppm or more, and particularly at 5 ppm or more, the reaction time is within 2 minutes as shown in FIG. An excellent bactericidal effect of 2.5D or less below the limit was observed. That is, it was confirmed that the sterilizing effect of test C using low-concentration chlorine water for sterilization treatment was superior to the sterilizing effect of test A using slightly acidic electrolyzed water for sterilization treatment.

  The sterilization method according to the present embodiment performs a sterilization pretreatment in contact with an alkaline aqueous solution prior to sterilization with low-concentration chlorine water. Thereby, the outstanding bactericidal effect beyond the bactericidal effect of the sterilization method which concerns on the said 1st Embodiment can be acquired also with respect to the spore which cannot obtain a bactericidal effect only by low concentration chlorine water. The mechanism is assumed to be the same as that of the first embodiment.

  Next, the Example which applied this invention to the specific production process is shown. The sterilization method according to the above embodiment is suitable for a bottle washing process for glass bottles such as municipal milk that is recycled. This type of glass bottle may be contaminated with Bacillus cereus during the recycling process and adhere to highly resistant Bacillus cereus and other spores. It is extremely important for safety and health to prevent food poisoning due to this. This is because it is a difficult task.

  For example, FIG. 12 shows the washing bottle equipment, and a plurality of washing water tanks 1 (here, 4 tanks) storing washing water containing a cleaning chemical and a rinse water tank 2 (here, 1 tank) storing purified water. ), And a rinsing device 3 that performs spray cleaning with purified water, and a conveying device 4 that conveys the glass bottle so that each washing water tank 1, the rinsing water tank 2, and the rinsing device 3 can be successively processed in this order. Although not shown, the washing water tank 1 and the rinsing water tank 2 are also provided with heating equipment for heating the stored washing water and rinsing water, circulation filtration equipment for maintaining water quality, and the like.

  The glass bottle is transported in the direction of the arrow in FIG. 12 by the transport device 4 and continuously immersed in the cleaning water of each cleaning water tank 1 to gradually remove foreign matter and dirt attached to the recovered glass bottle. (Cleaning process). Next, by immersing in clean water in the rinse water tank 2 and spray-cleaning the inside and outside of the glass bottle with the rinse device 3, the wash water adhering to the glass bottle is washed away with clean water (rinse process). In the cleaning process, there may be a cleaning water spray process in which cleaning water is sprayed in addition to the immersion process. The time required for the series of washing steps is about 8 to 10 minutes.

  Next, sterilization is performed using equipment similar to the previous washing bottle equipment. The washed glass bottle is continuously subjected to a sterilization process in which it is sterilized with a high-concentration sodium hypochlorite aqueous solution (high-concentration chlorine water) such as 200 ppm and a rinsing process in which the high-concentration chlorine water is washed away. The flow of the series of washing bottle processes is shown in FIG. The sterilization method according to the above embodiment is applied to this washing bottle process.

(Example 1)
First, an example in which the sterilization method according to the first embodiment is applied to the conventional bottle washing process shown in FIG. That is, as shown in FIG. 13 (a), the sterilization step with high-concentration chlorine water and the subsequent rinsing step are performed by the pre-sterilization step with the predetermined alkaline aqueous solution and the slightly acidic electrolyzed water according to the first embodiment. Replace with sterilization process. For example, when sterilization is performed using the washing bottle facility shown in FIG. 12, the predetermined alkaline aqueous solution according to the first embodiment is used in place of the washing water stored in the washing water tank 1 and stored in the rinse water tank 2. The predetermined slightly acidic electrolyzed water according to the first embodiment is used instead of the purified water sprayed with the purified water and the rinse device 3.

  Specifically, the glass bottle rinsed in the rinsing process is immersed in a washing water tank 1 in which an aqueous NaOH solution having a pH of 11 to 14 and a water temperature of 50 to 80 ° C. is stored for 5 to 10 minutes. (Pre-sterilization process). NaOH is an inexpensive strong alkaline agent and is widely used in food production facilities and is therefore suitable for an alkaline aqueous solution. The reason why the pH is 11 or more is that if it is more than this, inactivation of the enzyme is recognized and it is effective for denaturation of the protein. If the water temperature is 50 ° C. or higher, the protein denaturation action by heating is obtained, which is more effective, and bacteria cells other than spores, molds and yeasts can be sterilized. However, if it exceeds 80 ° C., the glass bottle itself may be damaged, and the thermal efficiency is also deteriorated. Therefore, the temperature is preferably set to 80 ° C. or lower.

  Subsequently, the glass bottle treated with the NaOH aqueous solution is immersed in a rinse water tank 2 in which slightly acidic electrolyzed water having a pH of 4 to 7 and an effective chlorine concentration of 1 to 50 ppm is stored. It is sterilized by spraying acidic electrolyzed water (sterilization process). A higher effective chlorine concentration is preferable, but if it exceeds 50 ppm, problems such as residual chlorine odor occur, so it was set to 50 ppm or less. Under such conditions, the problem of off-flavor such as chlorine odor and trihalomethane can be solved at once, and spores can be effectively sterilized. In particular, if the effective chlorine concentration is set in the range of 5 to 20 ppm, even a highly resistant Bacillus cereus spore can reliably obtain a bactericidal effect of 2.6D or more in a short time of 5 minutes or less. In order to completely remove residual chlorine, a rinsing process with purified water may be provided at the end of the sterilization process. However, even in this case, a large amount of rinsing water should be unnecessary. The water temperature of the slightly acidic electrolyzed water may be room temperature and may be set to about 20 ° C.

  FIGS. 13B and 13C show another application example. There, the sterilization method according to the first embodiment is further incorporated into the washing bottle process so that the series of processes can be greatly simplified.

  In FIG. 13B, the alkaline aqueous solution is used instead of the washing water used in the washing step, so that the washing step also serves as the pre-sterilization step shown in FIG.

  Specifically, in the case of the washing bottle facility shown in FIG. 12, instead of the washing water stored in each washing water tank 1, the pH is set in the range of 11 to 14 and the water temperature is set in the range of 50 to 80 ° C. An aqueous NaOH solution may be used. By doing so, for example, if the washing bottle facility shown in FIG. 12 is used for sterilization, the washing water tank 1 used in the pre-sterilization process can be eliminated, and a series of processes from the cleaning process to the sterilization process can be eliminated. The washing bottle process can be simplified and the amount of chemicals and water used can be greatly reduced.

  In (c) of FIG. 13, in addition to combining the previous washing step and the pre-sterilization step shown in FIG. 13 (a), a predetermined slightly acidic electrolyzed water is used in place of the purified water used in the rinsing step. Accordingly, the rinsing process is also used as the sterilization process shown in FIG. 13A, so that the sterilization process can be performed with only one washing bottle facility.

  Specifically, in the washing bottle facility shown in FIG. 12, an aqueous NaOH solution having a pH of 11 to 14 and a water temperature of 50 to 80 ° C. instead of the washing water stored in each washing water tank 1. In addition to the purified water stored in the rinsing water tank 2 and the purified water sprayed by the rinsing device 3, slightly acidic electrolyzed water having a pH of 4 to 7 and an effective chlorine concentration of 1 to 50 ppm is used. . By doing so, the equipment used for sterilization becomes unnecessary, and a series of washing bottle processes can be greatly simplified. The amount of water used can also be dramatically reduced, greatly improving productivity.

(Example 2)
Next, an example in which the sterilization method according to the second embodiment is applied to the conventional bottle washing process shown in FIG. The following description will focus on the differences from the first embodiment, and the description of the same points as in the first embodiment will be omitted.

  Specifically, in the sterilization step shown in FIG. 13 (a), low-concentration chlorine water having a pH of 6.5 to 9.0 and an effective chlorine concentration of 1 to 50 ppm in place of the slightly acidic electrolyzed water. Is used. That is, a glass bottle that has been subjected to a pre-sterilization process using an aqueous NaOH solution is immersed in a rinsing water tank 2 in which low-concentration chlorine water is stored, and sterilization treatment is performed by spraying low-concentration chlorine water with a rinse device 3. (Sterilization process). In addition, the water temperature of low concentration chlorine water may be normal temperature, and should just set to about 20 degreeC.

  At this time, since the rinse process performed after the sterilization process using low concentration chlorine water can be omitted, the amount of water to be used can be reduced. However, as with the slightly acidic electrolyzed water, the effective chlorine concentration of the low-concentration chlorine water was set to 50 ppm or less in consideration of the residual chlorine odor and the like. Under such conditions, it is possible to solve problems of off-flavor such as chlorine odor and trihalomethane at once, and spores such as Bacillus cereus can be effectively sterilized. In particular, if the effective chlorine concentration of low-concentration chlorine water is set in the range of 5 to 20 ppm, even a highly resistant spore such as Bacillus cereus can reliably obtain a bactericidal effect of 2.5D or more in a short time of 2 minutes or less. Can do.

  As in the above embodiment, a rinsing process with purified water may be provided at the end of the sterilization process in order to completely remove residual chlorine. Even in this case, a larger amount of rinsing water should be unnecessary than when high-concentration chlorine water is used.

  Further, in contrast to the application examples shown in FIGS. 13B and 13C described in the above embodiment, low-concentration chlorine water can be used instead of the slightly acidic electrolyzed water. Also for the application examples shown in FIGS. 13B and 13C, a rinsing step for completely removing residual chlorine may be provided.

  In Example 1 and Example 2, the alkaline aqueous solution may be not only an aqueous solution of NaOH alone but also an aqueous solution containing other chemicals (for example, Ecrine No. 110 aqueous solution).

It is a graph which shows the sterilization effect in the process before sterilization alone in the sterilization method concerning a 1st embodiment. It is a graph which shows the test result (effective chlorine concentration of 1 ppm) of the sterilization method concerning a 1st embodiment. It is a graph which shows the test result (effective chlorine concentration of 5 ppm) of the sterilization method concerning a 1st embodiment. It is a graph which shows the test result (effective chlorine concentration of 10 ppm) of the sterilization method concerning a 1st embodiment. It is a graph which shows the test result (effective chlorine concentration of 20 ppm) of the sterilization method concerning a 1st embodiment. It is a graph which shows the relationship between the reaction time in the sterilization method which concerns on 1st Embodiment, and the sterilization effect in each effective chlorine density | concentration of 5-20 ppm. It is a graph which shows the test result (effective chlorine concentration of 1 ppm) of the sterilization method concerning a 2nd embodiment. It is a graph which shows the test result (effective chlorine concentration of 5 ppm) of the sterilization method concerning a 2nd embodiment. It is a graph which shows the test result (effective chlorine concentration of 10 ppm) of the sterilization method concerning a 2nd embodiment. It is a graph which shows the test result (effective chlorine concentration of 20 ppm) of the sterilization method concerning a 2nd embodiment. It is a graph which shows the relationship between the reaction time and the bactericidal effect in each effective chlorine density | concentration of 5-20 ppm in the sterilization method which concerns on 2nd Embodiment. It is a conceptual diagram of a washing bottle equipment. It is a process flow figure for explaining a concrete sterilization method.

Explanation of symbols

1 Washing water tank 2 Rinse water tank 3 Rinse device 4 Conveying device

Claims (14)

A pre-sterilization step of contacting the food container with an alkaline aqueous solution;
A sterilization step of sterilizing the food container in contact with the alkaline aqueous solution with hypochlorous acid-containing water;
A food container sterilization method comprising: In the food container sterilization method according to claim 1,
The said alkaline aqueous solution is NaOH aqueous solution, pH is the range of 11-14, The water temperature is set to the range of 50-80 degreeC, The sterilization method of the food container characterized by the above-mentioned. In the sterilization method of the food container according to claim 1 or 2,
The method for sterilizing a food container, wherein the hypochlorous acid-containing water is slightly acidic electrolyzed water, and has a pH in the range of 4 to 7 and an effective chlorine concentration in the range of 1 to 50 ppm. In the sterilization method of the food container according to claim 1 or 2,
The hypochlorous acid-containing water is a sodium hypochlorite aqueous solution, having a pH of 6.5 to 9 and an effective chlorine concentration of 1 to 50 ppm. Sterilization method. A washing step of washing the bottle with washing water;
A rinsing step of rinsing the washed bottle with water;
A pre-sterilization step of bringing the rinsed bottle into contact with an alkaline aqueous solution;
A sterilization step of sterilizing the bottle in contact with the alkaline aqueous solution with slightly acidic electrolyzed water;
A food container sterilization method comprising: A washing step of washing the bottle with washing water;
A rinsing step of rinsing the washed bottle with water;
A sterilization step of sterilizing the rinsed bottle with slightly acidic electrolyzed water;
With
The washing water used in the washing step is an alkaline aqueous solution, and the washing step also serves as a pre-sterilization step. A washing step of washing the bottle with washing water;
A rinsing process for rinsing the washed bottle;
With
The washing water used in the washing step is an alkaline aqueous solution, the water used in the rinsing step is slightly acidic electrolyzed water, the washing step serves as a pre-sterilization step, and the rinsing step serves as a sterilization step. A method for sterilizing a food container. In the method for sterilizing a food container according to any one of claims 5 to 7,
The said alkaline aqueous solution is NaOH aqueous solution, pH is the range of 11-14, The water temperature is set to the range of 50-80 degreeC, The sterilization method of the food container characterized by the above-mentioned. In the method for sterilizing a food container according to any one of claims 5 to 7,
The method for sterilizing a food container, wherein the slightly acidic electrolyzed water has a pH of 4 to 7 and an effective chlorine concentration of 1 to 50 ppm. A washing step of washing the bottle with washing water;
A rinsing step of rinsing the washed bottle with water;
A pre-sterilization step of bringing the rinsed bottle into contact with an alkaline aqueous solution;
A sterilization step of sterilizing the bottle in contact with the alkaline aqueous solution with an aqueous sodium hypochlorite solution;
A food container sterilization method comprising: A washing step of washing the bottle with washing water;
A rinsing step of rinsing the washed bottle with water;
A sterilization step of sterilizing the rinsed bottle with a sodium hypochlorite aqueous solution;
With
The washing water used in the washing step is an alkaline aqueous solution, and the washing step also serves as a pre-sterilization step. A washing step of washing the bottle with washing water;
A rinsing process for rinsing the washed bottle;
With
The washing water used in the washing step is an alkaline aqueous solution, the water used in the rinsing step is a sodium hypochlorite aqueous solution, the washing step is a pre-sterilization step, and the rinsing step is a sterilization step. A method for sterilizing food containers, which also serves as both. The method for sterilizing a food container according to any one of claims 10 to 12,
The said alkaline aqueous solution is NaOH aqueous solution, pH is the range of 11-14, and the water temperature is set to the range of 50-80 degreeC, The sterilization method of the food container characterized by the above-mentioned. The method for sterilizing a food container according to any one of claims 10 to 12,
The aqueous sodium hypochlorite aqueous solution has a pH of 6.5 to 9 and an effective chlorine concentration of 1 to 50 ppm.

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